Ernie Gehr is a precise filmmaker who aims for perfection in every project. Often he bases a whole movie on a single visual idea, methodically and meticulously worked out. It's a credit to his artistry that the results -- in his best work -- are as pleasing to the eye and emotions as they are to the mind.In a recent one-man show at the Millennium film workshop, Gehr introduced a couple of past efforts followed by three (untitled) premieres. The program opened with ''Table,'' in which a piece of furniture is seen from two rapidly alternating perspectives; and ''Shift,'' in which traffic on a city street forms painterly and frequently amusing patterns on the screen.
While one of the premieres was a rather academic study of dense horizontal lines, two of the new films made further masterly use of subtly off-balance camera angles. One was a long study of people on a busy sidewalk, caught in fragmentary glimpses from unexpected vantage points -- a colorful and sometimes dizzying montage that is unfortunately weakened by having too few variations to support its high energy level and substantial length. The other new work was an undiluted masterpiece, however: a single shot of snow falling in front of a brick wall as the focus slowly changes from foreground to background. An ingenious conception scrupulously realized, it's as good a movie as I've seen in ages, and proof that Gehr is at the forefront of today's ''experimental'' cinema.